Medical instruments employed in image-guided surgery must be calibrated, verified and/or validated prior to use. In other words, the precise dimensions, configuration or arrangement of the instrument must be known. Otherwise, healthy tissue that lies next to target tissue may be inadvertently operated on due to an unknown or deformed instrument, e.g., due to instrument bending.
A device and a method for calibrating a bent element are known from EP 1 413 258 A1, wherein the bent element is connected to a navigation element. The element also is attached to a calibration device, and the element is moved until the element is calibrated.
Navigationally calibrating medical instruments or implants is known from EP 1 369 090 A1, wherein a spatial position of the instrument or implant is ascertained by means of a medical navigation system. The position of the instrument or implant then can be ascertained relative to anatomical data, wherein the spatial orientation of a multi-dimensionally designed, functional section of the instrument or implant also can be ascertained.
U.S. Pat. No. 6,428,547 B1 describes recognizing the shape of a treatment apparatus, wherein the treatment apparatus is referenced in a computer-controlled, camera-assisted navigation system by means of a marker array attached to the treatment apparatus. Projections of the treatment apparatus are detected by means of x-ray recordings, and the shape of the treatment apparatus is assigned to the projections in the navigation system based on the position of the marker array in the projections.
A verification method for positions in camera images is known from U.S. Pat. No. 6,724,922 B1.
DE 199 44 516 A1 describes a method for detecting the shape of an object, wherein a camera image of the object is produced and an outline of the object is detected in a first plane by an evaluation unit connected to the camera. A focusing distance of the camera then is altered and an outline of the object is detected by the evaluation unit in a second plane. These steps are repeated until a sufficient number of outlines have been detected, such that the spatial shape of the object can be established.